Die-casting machine



May 8, 1934. 1.. H. MORIN DIE CASTING MACHINE Filed Feb. 16, 1932 =1 NVENTOR- ATTORNEY- Patented May 8, 3934 DIE-CASTING MACMNE Louis H. Morin, New York, N. Y., assignor to Doehler Die-Casting 00., a corporation of New York Application February 16, 1932, Serial No. 593,221

12 Claims.

My invention relates to a die-casting machine and in particular to a machine of the type shown in my copending application Serial No. 513,803 filed February 6, 1931, for Die casting.

The machine disclosed in my prior application is for carrying out my method of die-casting substances having a relatively high melting point as compared with the metals commonly used in diecasting, and substances which are viscous when in the molten state. This machine includes a pressure end wherein the substance to be diecast is forced into the mold cavity of the are, and a power end which opens and closes the die and ejects the casting. The pressure end of the 15 machine includes a pressure chamber into which the substance to be die-cast is introduced. An orifice through the wall of the pressure chamber communicates with the mold cavity of a die and constitutes a discharge orifice through which the substance to be die-cast is forced into the mold cavity.

Within this pressure chamber there is movably mounted a piston which is movable within the pressure chamber to cover and uncover the discharge orifice. The face of the piston forms one end wall of the pressure chamber. Opposed to this piston and acting within the pressure chamber, there is a plunger which exerts a pressure upon the substance within the pressure chamber to cause that substance to flow through the discharge orifice. As the plunger moves towards the piston it forces the piston against the end of the pressure chamber and then squeezes the substance in the pressure chamber against the face of the piston. After sufficient metal has been forced through the discharge orifice to fill the mold cavity of the die, the plunger is withdrawn. Usually, the substance remaining in the pressure pot solidifies and the piston is drawn in 40 the direction of the plunger and shears the portion of the substance remaining in the pressure chamber from that portion which is in the discharge orifice.- This shearing action causes a shock which places a strain upon the piston and its associated parts.

Another difiiculty which I have found in practice is that when the plunger is made to fit snugly within the pressure chamber, it sticks to the walls thereof, and when the plunger is made to form a loose fit so as to act freely in the pressure chamher, the substance within the pressure chamber flows along the side of the plunger between the plunger and the walls of the pressure chamber.

By my present invention, I have improved the 55 construction of the pressure end of the machine and I am enabled to have the plunger freely movable in the pressure chamber and at the same time prevent the excretion of the substance under pressure along the side of the plunger. I accomplish this feature of my invention by providing means associated with the'plunger for collecting a portion of the substance in the pressure chamber and forming a seal therewith between the plunger and the wall of the pressure chamber.

An advantage of my improved construction is 5 the fact that I provide means for shearing the substance remaining in the pressure chamber from the portion of the substance in the discharge orifice while the piston is in its innermost position in the pressure chamber.

A feature of my improved construction is the fact that the surface opposed to the plunger is slightly curved which, I have found, 'causes the molten substance in the pressure chamber to flow more readily toward and through the discharge orifice of the pressure chamber when acted upon by the plunger.

Specifically, the active face of the piston in the pressure chamber, or that face opposed to the active face of the plunger is slightly convexed and. as the substance, in the fiuid state, is pressed against this surface, it flows much more readily towards and through the discharge opening of the pressure chamber. Adjacent the active face of the plunger there is formed a circumferential groove in the side of the plunger. As the plunger moves in the pressure chamber to place the substance therein under pressure, a portion of the substance flows along the side of the plunger to this circumferential groove. The substance enters the circumferential groove and solidifies therein, forming a seal between the plunger and the wall of the pressure chamber which seal prevents any of the substance from passing this point of the plunger.

In the innermost position of the piston the active face thereof is above the discharge opening. Grooves are, however, formed on the side of the piston which extend along the side of the piston a sufiicient distance to communicate with 100 the discharge orifice when the piston is in its innermost position. After the mold cavity of a die has been filled, the piston, while in its innermost position, is turned about its longitudinal axis 105 and the edge of the groove in the side thereof shears the portion of the substance remaining in the pressure chamber from the portion in the discharge orifice. The piston is then moved in the pressure chamber to discharge that portion 110' of the substance which remains in the pressure chamber.

The several features of the machine ofmy present invention will be more clearly understood from the following particular description of one embodiment thereof which is shown in the accompanying drawing in which:

Fig. l is an end view of the pressure end of a die-casting machine constructed in accordance with my invention, the pressure chamber thereof being illustrated in section;

Fig. 2 is also an end elevation of the same, illustrating theparts thereof in a different position;

Fig. 3 is a sectional plan view taken on the line 33 of Fig. 1; and

Fig. 4 is an enlarged fragmentary section of the piston illustrating the shape of the active face thereof.

In the drawing, I have illustrated the pressure end of a die-casting machine similar to that shown in my copending application hereinbefore referred to. As shown in the drawing the pressure chamber 1 which is formed in a solid metal block 2 is mounted upon a bed plate 3 which is supported by the frame of the machine. The block 2 has an opening formed through one side thereof which communicates with the pressure chamber. In this opening, there is a bushing 4 having a collar 5 abutting against the outer surface of the side of the pressure chamber. The bushing has a longitudinal tapered opening therethrough which constitutes the discharge orifice of the pressure chamber.

Within this pressure chamber, there is slidably mounted a piston 6 which is formed on the end of a rod 7 that passes through the bottom of the pressure chamber and the bed plate on which the pressure chamber is mounted. The bottom of the pressure chamber is frusto-conical in shape and the inner end of the piston opposed thereto is complementaryin shape. The face 8 of the piston is slightly convexed, the slightest convexity being sufficient to produce a more ready flow of the fluid substance in the pressure chamber towards the discharge orifice. As will be seen in Fig. 1, when the piston is in its innermost position in the pressure chamber, the face thereof is above the level of the discharge orifice. In the side of the piston, however, there is formed one or more longitudinal grooves 9 which extend down the side of the piston, longitudinally thereof, below the level of the discharge orifice of the pressure chamber. These grooves constitute communicating passages from the face of the piston to the discharge orifice. Near the bottom of the piston, there is formed a circumferential groove 10 which is semi-circular in cross section.

Above the pressure chamber, there is mounted a cross-head 11 that is slidably mounted upon supporting rods 12 extending from the bed plate and secured thereto. The cross-head, on the lower side thereof, carries a plunger 13 in direct alignment with the pressure chamber. This plunger acts within the pressure chamber and is adapted to squeeze any substance within the pressure chamber against the face of the piston therein to force that substance through the discharge orifice. The plunger is of such a diameter that it acts freely within the pressure chamber. Adjacent the active end of the plunger, there is formed in the side of the plunger a circumferential groove 14 similar to the circumferential groove formed in the piston. When the plunger moves into the pressure chamber and places 9.

fluid substance therein under pressure, a portion of that substance flows along the side of the piston between the piston and the wall of the pressure chamber. This substance flows into the groove 14 and solidifies therein. In the solidified state, the substance collected in the groove forms a seal between the plunger and the walls of the pressure chamber and prevents material from passing this point. As the plunger is moved out of the pressure chamber, the material solidified in the groove may be brushed or blown, by compressed air, from the groove in the plunger. The groove in the piston acts in the same manner.

Above the cross-head, on the upper ends of the supporting rods 12 there is mounted a fluid pressure motor 15. This motor has two side lugs 16 through which a reduced portion of the supporting rods pass, the lugs resting upon the shoulders formed by reducing the supporting rods. The motor is held in'place on these supporting rods by nuts 17 threaded into the ends of the rods. The piston rod extending from this motor is secured to the upper side of the cross-head and the motor operates to move the cross-head, and consequently the plunger secured thereto, up and down the supporting rods and into and out of the pressure chamber.

The piston rod extending from the piston in the pressure chamber, is reduced in diameter, near its lower end to form a shoulder 18 and the reduced portion of the rod has formed therein a pair of helical cam grooves 19. Against the shoulder l8 and operating cross-bar 20 is adapted to abut to lift the rod and move the piston to a position in which the face thereof extends above the upper end of the pressure chamber. This cross-bar is carried by two rods 21 to which it is secured and which extend through and are secured to lugs 22 formed on the sides of the cross-head. The cross-bar thus moves with the cross-head.

In the cross-bar, there is formed a depression near the upper surface thereof and in this depression there is mounted two blocks 23 which are pressed towards the piston rod by means of springs 24. A hand lever 25 having a hook-shaped cam 26 on the inner end thereof extends into this depression and acts on cam followers 27 to separate the blocks in opposition to the springs acting thereon. Each of these blocks has cam projections 28 formed on the ends thereof. As the cross-head moves downwardly to a point adjacent the end of the piston rod these blocks are held outwardly by the position of the lever 25. When the cross-bar has reached its lowermost position the lever is moved so that the cams become disengaged from the cam followers and the blocks are permitted to move under the action of the springs towards the piston rod. The cam projections on the blocks enter the helical grooves in the lower end of the piston rod and as the cross-head and cross-bar move upwardly the engagement of these cam projections with the helical groove causes the piston in the pressure chamber to be rotated about its longitudinal axis. This rotation of the piston shears the portion of the substance remaining in the pressure chamber from that portion in the discharge orifice. As the cross-bar reaches the shoulder formed by reducing the diameter of the piston rod, it engages the shoulder and raises the piston to the position shown in Fig. 2, in which position the solidified substance which remains in the pressure chamber may be removed from the piston. The hand lever may then be shifted to separate the blocks and release the piston rod and the piston will then descend to the inner end of the pressure chamber in which position the machine is again ready to receive a charge of molten substance.

It will be obvious that various changes may be made by those skilled in the art in the details of the embodiment herein described within the principle and scope of my invention as expressed in the appended claims.

1- claim:

1. In a die-casting machine, a pressure chamber having an orifice through one wall thereof and adapted to receive the substance to be diecast, a plunger mounted to act in said pressure chamber for exerting a pressure upon the substance therein and forcing the substance to fiow through the orifice in the wall of the pressure chamber, the plunger having a circumferential groove formed therein for collecting a portion of the substance to be die-cast passing along the side of the plunger and forming a seal therewith between the plunger and the wall of the pressure chamber.

2. In a die-casting machine, a pressure chamber having an orifice through a wall thereof and adapted to receive the substance to be die-cast, a piston slidably mounted within the pressure chamber and being movable to cover and uncover the orifice in the wall thereof, a plunger mounted to act in the pressure chamber for squeezing the substance therein against the face of the piston to cause the substance to flow through the orifice through the Wall of the chamber, the plunger having a circumferential groove formed in the side thereof for collecting a portion of the substance to be die-cast passing along the side of the piston and forming a seal therewith between the plunger and the wall of the pressure chamber.

3. In a die-casting machine, a pressure chamber having an orifice through a wall thereof and adapted to receive the substance to be die-cast, a piston slidably mounted within the pressure chamber and being movable to cover and uncover the orifice in the wall thereof, a plunger mounted to act in the pressure chamber for squeezing the substance therein against the face of the piston to cause the substance to flow through the orifice through the wall of the chamber, the plunger and the piston each having a circumferential groove formed in the side thereof for collecting a portion of the substance to be die-cast and forming a seal therewith between the plunger and the wall of the pressure chamber and between the piston and the wall of the pressure chamber.

l. in a die-casting machine, a pressure chamher having an orifice through the wall thereof and adapted to receive the substance to be diecast, a plunger mounted to act within the pressure chamber for exerting a pressure on the substance therein to cause the substance to fiow through the orifice, and a piston having a curved face slidably mounted within the pressure chamber and being movable to cover and uncover the orifice through the wall thereof, the curved face of the piston constituting the surface of, the pressure chamber against which the substance therein is pressed by the plunger.

5. In a die-casting machine, a pressure chamber having an orifice through the wall thereof and adapted to receive the substance to be diecast, a plunger mounted to act within the pressure chamber for exerting a pressure on the substance therein to cause the substance to fiow through the orifice, and a piston having a con- ..vexedly curved face slidably mounted within the pressure chamber and being movable therein to cover and uncover the orifice through the wall thereof, the convexed face of the piston constituting the surface of the pressure chamber against which the substance therein is pressed by the plunger.

6. In a die-casting machine, a pressure chamber adapted to receive the substance to be diecast and having an orifice through the wall thereof, a piston slidably mounted within the pressure chamber and having a longitudinal recess in the side thereof adapted to communicate with the orifice when the piston is in the innermost posiiion, means for exerting a pressure upon a substance within the pressure chamber to cause the substance to flow along the groove in the side of the piston and through the orifice in the wall of the pressure chamber, and means for moving the piston outwardly of the pressure chamber to eject the portion of the substance remaining in the pressure chamber, including means for rotating the piston to sever the portion of the substance remaining in the pressure chamber from that in the orifice.

7. In a die-casting machine, a pressure chamber adapted to receive the substance to be diecast and having an orifice through the wall thereof, a piston slidably mounted within the pressure chamber and having a longitudinal recess in the side thereof adapted to communicate with the orifice when the piston is in the innermost position, means for exerting a pressure upon a substance within ihe pressure chamber to cause the substance to flow along the groove in the side of the piston and through the orifice in the wall of the pressure chamber, and means for moving the piston outwardly of the pressure chamber to eject the portion of the substance remaining in the pressure chamber including means for rotating the piston while the piston remains in the innermost position to sever the portion of the substance remaining in the pressure chamber from that in the orifice.

8. In a die-casting machine, a pressure chamber adapted to receive the substance to be diecast and having an orifice through the wall thereof, a piston slidably mounted within the pressure chamber having a longitudinal recess in the side thereof adapted to communicate with. the orifice when the piston is in the innermost position, means for exerting a pressure upon a substance within the pressure chamber to cause the substance to flow along the groove in the side of the piston and through the orifice in the wall of the pressure chamber, a rod secured at one end to the piston in the pressure chamber and extending through the endwall of the pressure chamber, the rod having a helical cam groove extending along the side thereof and terminating in an abutment at the piston end of the groove, a reciprocating member movable longitudinally of the rod and having an opening therethrough for the passage of the rod, and cam elements on said member engaging the groove in the side of the rod and adapted to engage the abutment on the rod to move the piston outwardly of the pressure chamber.

9. In a die-casting machine, a member having a bore therein and an orifice communicating with the bore, the member forming a pressure chamber and being adapted to receive the substance to be die-cast, another member mounted to act in the bore of said first mentioned memher for exerting a pressure upon the substance therein and forcing the substance to flow through the orifice, and one of said members having a circumferential groove in the side thereof for collecting a portion of the substance to be diecast passing between the members along the sides thereof and forming a seal therewith between the members.

10. In a die-casting machine, a pressure chamber having an orifice through one wall thereof and adapted to receive the substance to be cast, an unconfined plunger mounted to act from a position exterior of the pressure chamber to a position within the pressure chamber for exerting a pressure upon a substance therein and forcing the substance to flow through the orifice in the wall of the pressure chamber, and means for forming a seal between the plunger and walls of the pressure chamber to prevent the molten substance therein from passing along the side of the plunger.

11. In a die-casting machine, a pressure chamber having an orifice through one wall thereof and adapted to receive the substance to be cast, a plunger mounted to act from a position exterior of the pressure chamber to a position within the pressure chamber for exerting a pressure upon the substance therein and forcing the substance to flow through the orifice in the wall of the pressure chamber, and. means on the side of the plunger for forming a seal between the plunger and the walls of the pressure chamber to prevent the molten substance therein from passing along the side of the plunger.

12. In a die-casting machine, a pressure chamber having an orifice through one wall thereof and adapted to receive the substance to be cast, a plunger mounted to act in said pressure chamber for exerting a pressure upon the substance therein and forcing the substance to fiow through the orifice in the wall of the pressure chamber, and means on the side of the plunger for forming with the molten substance in the pressure chamber a seal between the plunger and the walls of the pressure chamber to prevent the molten substance therein from passing along the side of the plunger.

LOUIS H. MORIN. 

